


Soulsick

by a-single-dinkling (nothin2cere)



Category: Undertale (Video Game)
Genre: Alternate Universe - Soulmates, Alternate Universe - Underfell, M/M, Monster sickness, kustard - Freeform
Language: English
Status: Completed
Published: 2017-02-21
Updated: 2017-02-21
Packaged: 2018-09-26 00:15:03
Rating: Teen And Up Audiences
Warnings: Creator Chose Not To Use Archive Warnings
Chapters: 1
Words: 2,912
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/9853262
Author URL: https://archiveofourown.org/users/nothin2cere/pseuds/a-single-dinkling
Summary: But, Sans mused as he stared numbly at the ceiling, monster souls behaved in strange ways; while human souls were powerful, determined, possessing the ability to change, monster souls were often confined to a strict set of rules that dictated their entire being. And when these rules broke, they broke in ridiculous ways.AKA what would happen if when a monster got sick, they're souls started acting up?Sans has dealt with this before, but soon finds himself with an entirely new problem altogether.





	

**Author's Note:**

  * For [RabbitPie](https://archiveofourown.org/users/RabbitPie/gifts).



> Phew this took a while!! I hope you enjoy!!
> 
> : )

_“SANS!! SANS!! COME LOOK!! THE ECHO FLOWERS ARE BLOOMING!!”_

 

_“heh, nice bro. they look kinda pretty all bunched together like that, don’tcha think?”_

 

_“YEAH, YEAH!! MAYBE PRETTY ENOUGH TO GIVE TO MY SOULMATE, HUH SANS??”_

 

_“sure pap, of course.”_

* * *

 

Souls were a finicky thing.

 

Sans had once called them a “big ball of who the fuck knows”, back when he and Papyrus were kids still learning their way in the world. Papyrus had chewed him out for that one; couldn’t have his brother using “improper language!”

 

Sans gave a quiet chuckle at the memory and winced, the dull throb beneath his bones becoming marginally stronger before fading. With great effort, he rolled over onto his back, hoping the cool air of the bedroom would help alleviate the ache in his bones.

 

When he had woken up this morning, the last thing Sans had expected would be another soul sickness, leaving him disoriented and anxious as to what exactly would go wrong this time.

 

But, Sans mused as he stared numbly at the ceiling, monster souls behaved in strange ways; while human souls were powerful, determined, possessing the ability to change, monster souls were often confined to a strict set of rules that dictated their entire being. A monster’s ATK and DEF, down to their appearance and personality, all hardcoded in the core of their being. And when these rules broke, they broke in ridiculous ways.

 

Sans held one stiff arm in front of his face from where he lay on the floor, eye sockets taking in the interweaving of magic coalescing between his radius and ulna. His torso was in a similar state, his summoned soul pumping out swathes of magic to rest in the spaces between his bones. Somehow during the night, his soul had decided it had no idea where to put his magic reserves anymore; and, Sans noticed not without some degree of amusement, instead opted to cover his body in the stuff like some kind of huge blue lantern.

 

Sans groaned, letting his arm fall limply to his side. Dimly, he wondered if this was cause enough to call in sick for work. He gave another dull chuckle.

 

Directly to Sans’ right a door unlocked, and the steady, thump-thump of steps descending the staircase alerted Sans to Papyrus, already up and starting his early morning routine for the new day.

 

 _early morning…_ Sans looked at his clock and inwardly cursed, suddenly acutely aware of his drooping eyelids and heavy limbs that showed he was up way too early for this.

 

 _well, I guess it doesn’t matter much anyway. no way I’m getting back to sleep with this light show in my ribcage._ A small grin appeared across Sans’ face. _I guess I’m not very de_ light _ed about this turn of events._

 

He gave himself a small pat on that back and a reminder to use it against Papyrus later in the day.

* * *

 

Sans made his way downstairs, grabbing the thickest jacket he could find to hopefully obscure the outpouring of magic from his souls. And, in a sluggish, insomnia induced haze, he walked over to the kitchen, where the banging of pots and pans and off-key singing emanated.

 

“WOW SANS, YOU’RE UP EARLY!! IT’S ALMOST 7 O CLOCK!!” Papyrus gave a quick turn of his head to acknowledge his presence, before turning back to focus on breakfast. Which appeared to be blackened bits of bacon interspersed with noodles. Sans had to give him credit, his attempts at ‘breakfast spaghetti’ sure were interesting.

 

“oh, you know me paps, always ready to help out my bro when he’s making breakfast.” Sans opened his eyes slightly to take in the sight of Papyrus crushing eggs and placing them in a pot to boil. Wait, was that a shell…?

 

“NYEH HEH HEH, WELL THAT WOULD CERTAINLY BE NICE IF THAT WERE TRUE!!” Papyrus accentuated the point with a flip of the pot of eggs as if he were making pancakes, the eggs sloshing around like a thick white slurry. Yup, those were definitely shells. “BUT I KNOW YOU WOULD SIMPLY ‘TASTE-TEST’ THE INGREDIENTS AND HIDE THE KITCHEN UTENSILS IN AN INFURIATINGLY COMICAL FASHION.”

 

Papyrus turned to glare at him, his face covered in egg whites. Sans fought hard to keep in his laughter. “well, what can I say? I just can’t help myself when something’s cooked by the great papyrus.”

 

Papyrus laughed quietly, and Sans closed his eyes, deep in contemplation. When was the last time he had gotten this sick? Clearly, one HP didn’t lend itself to a very healthy soul, but it wasn’t often he found himself with a figurative fountain of magic in his chest.

 

 _there was that one time my movement speed doubled, heh, couldn’t sit still for a week. that wasn’t fun._ Sans tapped his fingers against the table, leaning his head on his palm.

 

 _there was that other time my eyes got mixed up with muffet’s and had 8 eye sockets protruding out of my skull. was funny at first, but it wasn’t eye-see listening to people screamin’ all the time._ Sans cringed and began tapping his feet, feeling antsy. That one was a stretch.

 

 _oooh yeah, and that one time? when fruit started growing out of my chest? heh, that was a classic._ _Papyrus didn’t appreciate it much, though, said it was ‘cause they were melons-_ “hngh!”

 

Sans’ body gave a lurch, and all at once he was sprawled on the ground, seeing nothing but stars. What had been a dull ache this morning was now a burn as the magic surrounding his bones seemed to converge at his soul, burning bright hot. He tried to scream, but only a high-pitched keen came out. His limbs scrambled for purchase against the hard floor, trying desperately to get away from the burning penetrating deep into his soul.

 

“-ANS!! SANS CAN YOU HEA------ANS I’M HERE!! SANS!!”

 

Numbers flew by, too fast for him to even begin to comprehend. Sans could see many ones interspersed with zeroes, and occasionally some nines, but all he could focus on was the single 1 his magic gathered around that made the number blur at the edges, barely even recognizable anymore.

 

Sans’ vision blurred as he felt his magic surge in his soul, feeling bent out of shape. It was changing something…?

 

He blacked out, the last thing he saw being a single red 2.

* * *

 -----------------------------------------------------------------

UNIVERSE NUMBER INDICATION (UNI) CHANGED  
\-----------------------------------------------------------------

WOULD YOU LIKE TO CONFIRM?  
\-----------------------------------------------------------------

*YES* NO  
\-----------------------------------------------------------------

* * *

 

_“SANS, DO YOU THINK I’LL EVER HAVE A SOULMATE?”_

 

_“of course you will bro, everybody has one. hell, even I have one, so of course a cool dude like you is gonna have that special someone.”_

 

_“NYEH HEH, WELL, I AM VERY GREAT. BUT SANS, DON’T TALK SO BADLY OF YOURSELF!!! I’M SURE YOU’LL MEET YOUR SOULMATE, AND WHEN YOU DO YOU’LL SEE THAT YOU DESERVE HAPPINESS TOO!! AND MAYBE EVEN STEER YOU OFF THE PATH OF IRREMEDIABLE LAZINESS!!_

 

_“heheh, thanks, papyrus.”_

 

_“….SANS?”_

 

_“yeah bro?”_

 

_“HOW DO YOU KNOW YOU HAVE A SOULMATE?”_

 

 _“…..well, I guess it’s just this kind of tugging, deep in your soul…”_  

* * *

 

Sans gasped, and a rare burst of adrenaline caused him to push himself up against the cold snow around him. He feet fell out from under him, and his back fell hard against a tree, knocking the wind out of him and leaving him dazed. In the time it took for his soul to stop racing in his chest, Sans suddenly felt put off. Something was wrong….

 

 _wait, snow? how did I…._ Sans froze, eyes taking in the scene around him. Instead of the hardened tile of the kitchen, Sans’ feet now rested on the cold snow of Snowdin forest, deep enough into the trees that the darkened underbrush would block any light coming through if it had existed. In the distance, he could hear barking.

 

His breath came out in sharp gasps, and through the spinning of his mind came up with one coherent thought. In one quick motion, he brought his hand to his ribcage to steady his breathing, before reaching out with his magic to perform a Check.

\-----------------------------------------------------------------

SANS 1 ATK 1 DEF  
* you’re a little shaken up. A SOUL sickness has never been like this before…

\-----------------------------------------------------------------

“…still the same, huh..” Sans muttered, nearly bringing down his hand before he remembered the 1 his magic had changed, now a clearly defined 2. “guess I’ll have to go more in depth.”

 

Sans concentrated his magic, reaching out to the parts of his soul that he knew would contain certain STATS. His HP he came up with little trouble, still a measly 1. He felt a twinge of disappointment. With a little digging, he found his LV, also still at 1. That, at least, he could be grateful for.

 

 _what was that STAT called? UNI?_ Sans reached further.

 

“HEY!” Sans heard a sharp yell from across the trees, and he whipped his hand away from his chest scrambled to his feet, pressing his back flat against the tree behind him. That voice….  
In his concentration, Sans had failed to notice the barking, echoing across the forest, was now inexplicably closer. A churning in his gut told him that the menacing snarls which accompanied them would mean something very different than if he had met the dog pack back home. He glanced at the branches above, and concentrating his magic for a third time he pulled himself through a shortcut, landing gracelessly at one of the higher branches and gasping for breath.

 

No sooner had his slippers touched the bark did the barking suddenly stop, and in its place Sans could see the dark hoods of two dogs dart into view, their noses sniffing the ground in a manner almost comical had they not been snarling moments prior. The one on the left stood suddenly, the motion giving Sans a glance of the dog’s face before the hood was pulled over it again, filling Sans with immense confusion and dread.

 

was that...Dogamy? Except it couldn’t be. The Dogamy Sans knew had wide, blown out eyes, and a furry upper lip that feigned sternness but could become goofy in an instant. The dog down below betrayed no such kindness, its eyes beady and black and its snout pulled back in a scowl, revealing a set of sharpened teeth which Sans feared could tear him apart in an instant.

 

The dog, Dogamy, turned to the dog to his right, (Dogaressa, Sans guessed), and spoke in a series of barks that Sans could only assume meant something before their ears perked up to the sound of scuffling footsteps behind them.

 

Sans couldn’t see much, but when he got a good luck at the monster following behind him, his metaphorical heart leaped in his throat.

 

Standing behind the dogs was a small skeleton, a black coat and shorts being all that he could see of his attire. Adorning his face was a small speck of gold Sans could only assume was a good tooth, accentuating what seemed to be a mouth filled already with shark-like teeth. And his face was exactly the same as Sans.

 

Somehow, though, that managed to be the least concerning thing about the other skeleton. For when Sans set eyes on the other, a small, insistent tugging on his soul grew insistently stronger, one that he had long forgotten about. His eyes grew wide, and his hands gripped the fabric of his shirt, desperate to stop his soul from freaking out.

 

 _this isn't real, right?? this isn’t happening. I’m sick, my soul’s been acting up, hell, the guy down there is clearly ME, I’m just feeling things. why would I even, heh, why the HELL would I even be feeling it NOW of all times?? the guy isn’t even that good-looking! oh hell…_ Sans rested his head against the bark of the tree where he’d been grabbing, frantically trying to rationalize away the incessant beating in his soul, a tugging that he hadn't even _acknowledged_ in who knows how many years, missing the murmur of voices beneath him.

 

His jumbled thoughts were suddenly interrupted by a loud shout down below, showing the dogs and the other skeleton engaged in a shouting match.

 

“Well if my wife wasn’t so nose-blind, we’d have found the intruder by now!”

 

“Well maybe if you’d just listened and ran out when we first smelled the SOUL, we wouldn’t-”

 

‘It doesn’t matter! We smelled another little pup out here, and fresh EXP is too easy to pass-“

 

“STOP INTERRUPTING ME you big goon! We were going to go after the pup together, and Sansy here is just-“

 

“Yeah, this isn’t your job, Sansy. How about little pup goes and plays with the big pup, while the rest of us handle-“

 

Dogaressa growled, and in the blink of an eye the both of them were clawing at each other. The FIGHT was raging as the dogs clawed viciously, magic attacks tearing into each other’s armor when their teeth couldn’t reach. Sans stared in shock, almost appalled at the married couple’s spat that was emerging in front of him. Sure, Dogaressa and Dogamy would bicker occasionally, but never get physical with each other!

 

When their HP started dropping to dangerously low levels Sans tore his eye sockets away, but before Dogamy could land a devastating blow, red, sharpened bones appeared between them, effectively blocking Dogamy’s attack and giving Dogaressa the time to back away. But before she could try to launch a counter attack, the same bones encased her, trapping them both. The other skeleton had his bony hand raised, red magic at his fingertips like a weapon, his eyes dark. In one motion his hand had slammed both the dogs to the ground, and his eyes lit up in fury.

 

“THAT’S ENOUGH! I don’t know what the FUCK kind of intruder you two are talking about, but what I DO know is that grillby’s is having a special on mustard tomorrow, and I swear to god if I have to cover for you stupid mutt’s shifts again while you chase after fucking RABBITS, I’m going to dust someone.” The skeleton took a deep breath, before turning his glare into a smirk. “unless you’d rather I tell the boss about this?”

 

The dogs glared at the other skeleton before they cowed, their ears flattened to their heads. Sans could almost swear he heard a whimper.

 

“good,” the skeleton said slowly, but not before retracting his bone attacks so they scraped alongside the coats of the dogs, making them give small yelps in pain. Sans was dimly aware the attacks did only one damage.

 

The dogs fell onto their hindquarters and darted off into the woods, barking in a frenzy in their mad dash out of the forest. The skeleton turned to follow them, lazily stepping past one of the trees, before stopping. He inclined his head slowly upwards, and Sans could see the red in his eye lights.

 

“you can come down now, **s w e e t h e a r t**.”

 

Sans froze, but knew there was nothing else he could do. He’d been caught. He gathered his magic one last time, and with a pop appeared just a few feet away from the skeleton, staring into that one ruby eye light.

 

The skeleton gave a low chuckle, and with practiced movements turned slowly around, he eyes remaining closed. He seemed almost at ease, like he was the one completely in control.

 

“heheh, I gotta say, very clever how you hid up in the branches-“ The other Sans’ eyes had suddenly opened in shock, staring at Sans in a mixture of confusion and horror. The tugging returned again in his soul, this time much more forceful, but Sans resolved to ignore it. He instead kept his practiced grin on his face as the other skeleton slowly advanced.

 

For the longest time, neither of them moved. Sans’ expression was frozen in a smile that seemed too forced to be comfortable, while the other simply stared, a dull expression of shock still permuting his features. Then, as if coming to terms with something, the skeleton’s face became a scowl, and he loomed menacingly over Sans with the practice of someone who’s done it before.

 

“the hell do you think you’re doing, summoning your soul out here? are you looking to get dusted!?”  
Sans was lost. Was that concern? Or was the other skeleton about to dust him? He couldn’t find the words, coming out with a simple, unintelligible “uh..”

 

The other Sans gave a hefty sigh, his eye lights looking to the ceiling in what must be exasperation, before turning back to stare at him with some hint of an emotion Sans couldn’t identify.

 

“well, you ain’t in kansas anymore buddy. and someone’s gonna hafta teach ya how things work around here. guess I’ll hafta do.” The skeleton stuck his hand out, a gesture eerily similar to one Sans had performed countless times before. “The name’s sans, sans the skeleton. though I guess you already knew that.”

* * *

 

_"_ _HEY SANS? I JUST WANTED TO LET YOU KNOW, THAT UM, EVEN IF YOU FEEL SAD AND LONELY SOMETIMES, THAT UH, THERE’S SOMEONE OUT THERE FOR YOU!! AND WHEN YOU MEET THEM, YOU’RE GOING TO MAKE THEM VERY HAPPY!!”_

 

_“heh, well I hope they have a taste for jokes, cuz uh, I ain’t stopping anytime soon.”_

 

_“NYEHHH SANS!! I WAS BEING SERIOUS!!”_

 

_“yeah well, I was too….”_

**Author's Note:**

> I might continue this!! 
> 
> I wanted this to go on a little longer but i was already reaching almost 3,000 words lol. I'm interested in hearing what you guys think!


End file.
